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Memmie Lenglet edited this page Mar 16, 2015 · 1 revision

Notes about developement

Optimisations

Reduce HTTP loading time

The chunked encoding allow to reduce data awaiting, by sending it directly when data readed, without a full buffering. In addition, reduce memory usage. See RFC 2616 - HTTP Chunked Transfer Coding.

Speed up file reading

Use PHP native function ord() and chr() instead of more complete function pack() and unpack(). Reading or writing larger data blocs to manipulate it directly in memory (buffering).

Use database reading LOB (if data chunks are larger than 4Ko) http://php.net/manual/pdo.lobs.php

AS3 - Some technics :

TODO: use GZipCompression (work for server cache files nor for chunked encoding) http://code.google.com/speed/page-speed/docs/payload.html#GzipCompression

Sort and uniqueness

A quick method is using bit to save if a char is used or not: bit @0 = 1 if charcode U+0000 is present, bit @1 = 1 charcode U+0001 is present, etc.

[01000010 01000101 00000000 ...] give U+0001,U+0006,U+0009,U+0013,U+0015

Compared to nested loops (or indexOf()/lastIndexOf()), it reduce CPU usage, but potentialy use more memory:

  • For Basic Multilingual Plane (plane 0, BMP) -> 65536 values (U+0000-U+FFFF), require 8192 bytes
  • For all Unicodes Planes give 1114112 values (U+0000-U+10FFFF), require 139264 bytes. Can be reduced to 49152 bytes, if plane 3 to 13 are removed (720896 values, U+30000�U+DFFFF Unassigned plane)

Flash & JavaScript handle only 16 bits integers for characters code.

This method can't be used for highter bits numbers.

Example for uint32:

4294967296 values (`0x00000000` to `0xFFFFFFFF`), require 536870912 bytes (537MB)

In addition, the AVM take in memory 92 byte to store each ByteArray object.

To read presence of a charcode U+XXXX, use:

var charCode:uint = 0xXXXX;
var charCodeNeeded:Boolean = ((charMap[uint(charCode / 8)] >> (charCode % 8)) & 1) == 0;

To sort chars and get only uniques values:

var charCodeMap:ByteArray = new ByteArray();
charCodeMap.length = 8192;
var numChars:uint = 0;
for(i = 0; i < length; i++)
{
	var charCode:uint = value.charCodeAt(i);
	var byte:uint = charCodeMap[uint(charCode / 8)];
	if(((byte >> (charCode % 8)) & 1) == 0)
	{
		charCodeMap[uint(charCode / 8)] = byte | (1 << (charCode % 8));
		numChars++;
	}
}

var charCodes:Array = new Array(numChars), j:uint = 0;
for(i = 0, length = charCodeMap.length; i < length; i++)
{
	byte = charCodeMap[i];
	for(y = 0; y < 8; y++)
	{
		if(((byte >> y) & 1) == 1)
			charCodes[j++] = i * 8 + y;
	}
}

return String.fromCharCode.apply(null, charCodes);

Cache

Debugging

TODO: use memory_get_peak_usage() to trace memory usage (max).

TODO: use Xdebug

http://phplens.com/lens/php-book/optimizing-debugging-php.php

Transport and storage data format

TODO: use more open, documented and supported format rather than specific format such as WOFF (Web Open Font Format). It need for support of new Flash 10 text engine. Which use new data format: CFF (Compact Font Format) based on OTF (Open Type Font).

Command line

Shell scripting

PHP command line script can start with shebang (magic number #!) and location of followed by an command line interpreter, but not always at the same place on all UNIX compatible OS.

  • linux default: /bin/php
  • macport: /opt/local/bin/php
  • builtin php mac: /usr/bin/php

Solution: so use #!/usr/bin/env php to just use php executable whether it is This have no impact on script, # are used as simple line comment in PHP eq. of // comment.

#!/usr/bin/env php
<?php
echo 'test';
?>

this allow to execute script like that:

$ ./script.php

or execute by specify command line interpreter (windows compatible)

$ php script.php

Man page

Man pages are usually stored in /usr/man or usr/local/man in the manX/prog-name.X file, where X is the man page section example: /usr/man/man1/kill.1

Use nroff -man <manpage> to view the man page

CLI commands

Command line terminal screen can be controled by characters sequences to colorize, manipulate cursor, etc.

PHP Example: clear screen

<?php
echo chr(27)."[H".chr(27)."[2J";
?>
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